twos-complement

How to get 2's complement of a binary number in Java programmatically

由 我只是一个虾纸丫 提交于 2019-12-04 17:25:10
How to calculate the 2's Complement of a Hex number in Android/Java. For Example : String x = 10011010; 1's complement of x = 01100101; 2's complement is 01100110; How I can pro-grammatically achieve in Java? I had tried the following code to convert the binary to its 1's compliment: public String complementFunction(String bin) { String ones = ""; for (int i = 0; i < bin.length(); i++) { ones += flip(bin.charAt(i)); } return ones; } // Returns '0' for '1' and '1' for '0' public char flip(char c) { return (c == '0') ? '1' : '0'; } But I'm not able to get its two's complement. Thanks for your

Why Two's Complement?

由 限于喜欢 提交于 2019-12-03 17:13:40
问题 I'm writing a tutorial to teach kids (ages 9 to 13) about programming. I started with computers themselves, they don't have that much to do with computer science, it's more about the process involved with a solution to a computational problem. With that starting point, I'm guiding them toward an understanding that machines can help us with certain computational problems. People are great at abstract thinking and imagination, but computers are AWESOME at following a well-specified routine.

Detect one's or two's complement architecture in C++?

由 主宰稳场 提交于 2019-12-03 12:52:26
What is the most reliable way to detect whether the architecture uses one's or two's complement representation in C++? You shouldn't have to worry - there aren't too many ones complement machines out there :) But the easiest thing might be to compare "-1" with ~0. 来源： https://stackoverflow.com/questions/16501091/detect-ones-or-twos-complement-architecture-in-c

bitwise not operator

由 ℡╲_俬逩灬. 提交于 2019-12-03 02:13:01
问题 Why bitwise operation (~0); prints -1 ? In binary , not 0 should be 1 . why ? 回答1: You are actually quite close. In binary , not 0 should be 1 Yes, this is absolutely correct when we're talking about one bit. HOWEVER, an int whose value is 0 is actually 32 bits of all zeroes! ~ inverts all 32 zeroes to 32 ones. System.out.println(Integer.toBinaryString(~0)); // prints "11111111111111111111111111111111" This is the two's complement representation of -1 . Similarly: System.out.println(Integer

Why Two's Complement?

由 安稳与你 提交于 2019-12-03 02:08:45
I'm writing a tutorial to teach kids (ages 9 to 13) about programming. I started with computers themselves, they don't have that much to do with computer science, it's more about the process involved with a solution to a computational problem. With that starting point, I'm guiding them toward an understanding that machines can help us with certain computational problems. People are great at abstract thinking and imagination, but computers are AWESOME at following a well-specified routine. They can do it again and again, at amazing speed! Representing numbers in binary format has already been

Struct variable doesn't changed by assignment

由 无人久伴 提交于 2019-12-03 00:16:30
问题 struct st { int a1 : 3; int a2 : 2; int a3 : 1; } void main(void) { x.a3 = -1; if (x.a3 == -1) printf("TRUE\n"); else printf("FALSE\n"); x.a3 = 1; if (x.a3 == 1) printf("TRUE\n"); else printf("FALSE\n"); } In case, 'x.a3 = -1;' First if is TRUE . But, why 'x.a3 = 1' doesn't changed in second if ? It's still x.a3 = -1. And If I type 'x.a3 = 1;' in first if, it still x.a3 = = 1 !! It doesn't changed! Debug Result in XCode 回答1: The problem is, a signed 1 bit variable can hold only two values, -1

Finding how many bits it takes to represent a 2's complement using only bitwise functions

由 冷暖自知 提交于 2019-12-02 22:45:12
问题 We can assume an int is 32 bits in 2's compliment The only Legal operators are: ! ~ & ^ | + << >> At this point i am using brute force int a=0x01; x=(x+1)>>1; //(have tried with just x instead of x+1 as well) a = a+(!(!x)); ... with the last 2 statements repeated 32 times. This adds 1 to a everytime x is shifted one place and != 0 for all 32 bits Using the test compiler it says my method fails on test case 0x7FFFFFFF (a 0 followed by 31 1's) and says this number requires 32 bits to represent.

reversing two's complement for 18bit int

由 不羁的心 提交于 2019-12-02 18:15:12
问题 I have an 18 bit integer that is in two's complement and I'd like to convert it to a signed number so I can better use it. On the platform I'm using, ints are 4 bytes (i.e. 32 bits). Based on this post: Convert Raw 14 bit Two's Complement to Signed 16 bit Integer I tried the following to convert the number: using SomeType = uint64_t; SomeType largeNum = 0x32020e6ed2006400; int twosCompNum = (largeNum & 0x3FFFF); int regularNum = (int) ((twosCompNum << 14) / 8192); I shifted the number left 14

Bitwise xor 0xFFFFFFFF?

由 こ雲淡風輕ζ 提交于 2019-12-02 17:19:42
问题 I couldn't wrap my head around this: def expr(a): return ~(a ^ 0xFFFFFFFF), a ^ 0xFFFFFFFF, ~a, a print(expr(0xFFFFFFFF)) print(expr(1)) print(expr(0)) print(expr(-1)) I understand ~a means two's complement of a , but a ^ 0xFFFFFFFF also flips all the bits, but python will interpret it as a large number. I know Python3 is using unbound integer size, how does that work? Can someone ELI5 (Explain Like I'm Five)? Results: ( -1, 0, -4294967296, 4294967295) (-4294967295, 4294967294, -2, 1) (

bitwise not operator

由 瘦欲@ 提交于 2019-12-02 17:16:05
Why bitwise operation (~0); prints -1 ? In binary , not 0 should be 1 . why ? You are actually quite close. In binary , not 0 should be 1 Yes, this is absolutely correct when we're talking about one bit. HOWEVER, an int whose value is 0 is actually 32 bits of all zeroes! ~ inverts all 32 zeroes to 32 ones. System.out.println(Integer.toBinaryString(~0)); // prints "11111111111111111111111111111111" This is the two's complement representation of -1 . Similarly: System.out.println(Integer.toBinaryString(~1)); // prints "11111111111111111111111111111110" That is, for a 32-bit unsigned int in two's
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